Window of Opportunity
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Transcript of Window of Opportunity
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Window of Opportunity
Peter ScharfUniversity of Missouri
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Window of Opportunity?Window of Opportunity?
Sensors
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Factors defining the window
Effect of N timing on yieldHow late can you go?
Effect of sensor timing on diagnostic accuracyHow early can you go?
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0.0
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1.0
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0 4 8 12 16 20
growth stage of single N applic.
yiel
d r
elat
ive
to p
rep
lan
t N
missouri
nebraska
oklahoma
MO line
Effect of N timing on yield
tassel
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How late can you apply?
Planned single application: as late as V11?Northern data needed
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35 to 90 kg N/ha applied preplant
00.20.40.60.8
11.21.4
0 4 8 12 16 20
growth stage when balance of N applied
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
Effect of N timing on yield
tassel
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How late can you apply?
Planned single application: as late as V11?Northern data needed
With modest preplant N: later yet
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How late can you apply?
Planned single application: as late as V11?Northern data needed
With modest preplant N: later yet
As a rescue application: at least silking
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Factors defining the window
Effect of N timing on yieldEffect of sensor timing on
diagnostic accuracy
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Effect of sensor timing on accuracy
Can work as early as V6
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Effect of sensor timing on accuracy
Chlorophyll meter prediction of N rate V5 to V9, R2 = 0.53 V10 to R1, R2 = 0.66
Chlorophyll meter: equation changes as season progresses
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Prime window: V6 to V11?
Discussion?
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Effect of N timing on yield
Russelle et al. 1983 Evanylo 1991 Jokela and Randall 1989 Sripada et al. 2005 Miller et al. 1975 Hoeft Bausch
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Effect of N timing on yield depends on placement…
Broadcast
Between-row
0
2,000
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8,000
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0 30 60 90 120
Corn height (cm) when N was applied
Yie
ld (
kg h
a-1)
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…and source (N burn)(average of 7 locations in Missouri, 2003-04)
TreatmentTreatment 1 foot1 foot 2 feet2 feet 3 feet3 feet 4 feet4 feet
Ammonium Ammonium nitratenitrate 11 88 2020 1818
28% N 28% N solutionsolution 99 1414 3333 6161
UreaUrea 00 00 XX 44
Yield loss (between-row minus broadcast) when 150 lb N applied broadcast at corn height:
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Kansas producer 2006: 4000 Kansas producer 2006: 4000 acres of corn fertilized in six acres of corn fertilized in six days using sensorsdays using sensors
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…and source (N burn)(average of 7 locations in Missouri, 2003-04)
TreatmentTreatment 1 foot1 foot 2 feet2 feet 3 feet3 feet 4 feet4 feet
Ammonium Ammonium nitratenitrate 11 88 2020 1818
28% N 28% N solutionsolution 99 1414 3333 6161
UreaUrea 00 00 XX 44
Yield loss (between-row minus broadcast) when 150 lb N applied broadcast at corn height:
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Effect of N timing on yieldMissouri data, 28 expts. 1997-99
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growth stage of single N application
yie
ld r
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tiv
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t N
tassel
Scharf et al., 2002, Agron. J. 94:435-441
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Nebraska data, 2 expts. 1993-1994
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growth stage of single N application
yie
ld r
ela
tiv
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t N
Effect of N timing on yield
tassel
Binder et al., 2000, Agron. J. 92:1228-1236
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Oklahoma data, 5 expts. 2005-06
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0 4 8 12 16 20
growth stage of single N application
yie
ld r
ela
tiv
e t
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rep
lan
t N
Effect of N timing on yield
tassel
Walsh, 2006, MS Thesis
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35 to 90 kg N/ha applied preplant
0
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1
1.2
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0 4 8 12 16 20
growth stage when balance of N applied
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
nebraska
oklahoma
missouri
Effect of N timing on yield
tassel
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Effect of N timing on yield
Producer N rate, Producer N rate, preplant vs preplant vs sidedress (on sidedress (on average V9)average V9)
Field-length stripsField-length strips
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Effect of N timing on yield
YearYear # # expts.expts.
Yield effect of Yield effect of sidedresssidedress
20042004 77 -5-5
20052005 55 -16-16
20062006 55 +4+4
Yield effect is very weather-dependent!
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Yield response to late N: Only when corn hasOnly when corn has visible N stress visible N stress
Greenness of corn
Yield response to N applied when corn was shoulder-high
100% 0 91% 10 77% 37
Steve Watkins farm, Hayti, 2000; research by Gene Stevens
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Window of Opportunity: Later for unplanned (rescue) applications
Application until at least silking can give a large yield response when N stress is substantial
35 to 50 bu/ac in three MO tests